As disgusting as Conception II is in pretty much every possible aspect, there's still... Some kind of RPG going on in it, and..? I can't do this, Conception II is just awful.
To actually stay within the rules... Well, I've become a pretty big fan of the Atari 5200 lately, that covers the question a full system basis. The controllers ARE terrible and the library is VERY limited, but when you get past that (a controller mod helps), all the games are massive improvements over their 2600 equivalents in every possible way, and the unique titles like Space Dungeon are real standouts. If the financiers had seen the virtue in the designers' concepts for 2600 backwards compatibility and better quality controller parts, it could be a very different console world right now.
Also, I don't know if this counts as a trashy game per se, but I never hear anyone talk about it with respect, so I'll bring it up here - I think Egg Mania is one of the most crazy fun Versus Puzzle games of all time. It's simple to learn but has deceptive depth as to what stack tricks you can and can't get away with.